1. Field of the Invention
The invention relates to a bumper for motor vehicles comprising a transverse support to be mounted transversely to the longitudinal supports of the motor vehicle frame by means of impact damping members.
2. Description of the Related Art
Bumpers are arranged transversely at the front and rear of a motor vehicle between the plastic covering enclosing the car body and the frame of the motor vehicle. They are provided in order to prevent damage to the motor vehicle structure upon impact at low speed. For this purpose, impact damping members, so-called crash boxes, are provided between the transverse support and the longitudinal supports of the motor vehicle. The impact damping members are designed to absorb the energy resulting from an impact by converting the energy into deformation work.
Different types of bumpers or bumper arrangements are known. For example, German patent application DE 197 00 002 A1 discloses a bumper arrangement with a rigid support which is partly formed as a hollow support and fastened by means of an impact damping members to the front ends of the longitudinal supports of the chassis, respectively, on opposite sides of the longitudinal center axis of the motor vehicle. The transverse support is connected to a deformable bumper shell.
Similar proposals can be taken from British patent application GB 2 328 654 A or European patent application EP 0 050 722 A1.
Especially in the case of the rear bumper, the free deformation stroke which is available for energy absorption is short as a result of the motor vehicle construction because the available space is limited by the trunk cover. Therefore, it is desirable to form the transverse support already as a deformation element positioned upstream of the crash boxes in the direction of impact in the manner of a serial connection in order to provide energy absorption as high as possible from the beginning of the impact. Such systems are comprised usually of a transverse support which is embodied as a closed hollow chamber profile or as a closed pressed shell part, as is disclosed also in the above mentioned references. The weight of such a construction is relatively high because of the amount of material used. Also, painting or surface protection of the transverse support is complex because of the closed construction.